Spray apparatus

ABSTRACT

Spray apparatus of the kind having a liquid feed line connecting a supply of spray liquid and at least one spray nozzle, a return line from the spray nozzle to the supply and a pump for moving spray liquid from the supply to the at least one spray nozzle and for returning spray liquid from the at least one spray nozzle to the supply when the liquid is not being sprayed, characterised in that the liquid return line serves as at least a portion of the feed line when spraying.

BACKGROUND OF THE INVENTION

The invention relates to spray apparatus primarily for use in agriculture, although such apparatus may find application in horticulture or in industry generally.

Circulation in the boom spray lines of agricultural crop spray apparatus has become an increasingly important part of the modern machine. Inventions such as that known by the trade name LASER, see EP 0 820 224 B1 and sold by Knight Farm Machinery Limited and which concern the agitation of spray liquid in the spray lines to provide a simple addition to a standard sprayer or the more conventional pressurised circulation systems, are well known.

Spray line circulation was one of the early building blocks towards a modern sprayer design that is now increasingly influenced by environmental considerations.

One very significant area of concern is in the volume of spray liquid retained within the spray apparatus when the sprayer stops working. This is known as sprayer retained volume or SRV. Typically this could be as much as 100 litres or more. Recent work has been done to significantly reduce this by condensing the plumbing system of the sprayer and reducing the number of components. Today SRV can be as low as 20 litres on some machines but more typically would be around 50 litres.

Customers continue to ask for wider booms which obviously have to be fitted with spray lines. This results in more pipe-work and forces SRV upward. Any recirculation system adds to the pipe-work and increases the problem further.

With booms now being built up to 48 m in width, there are also pressure losses in the pipe-work that can affect the chemical output across the boom. This calls for bigger pipe-work, which increases retained volumes.

BRIEF SUMMARY OF THE INVENTION

With most sprayers the recirculation pipe-work is redundant when the sprayer is actually spraying. This is because we require as much pump flow as possible and would not want any flow to be bypassed. Also we normally monitor the flow to the boom for calibration purposes and therefore it is convenient to assume that all the flow is sprayed on the crop. Clearly this redundant pipe-work would be a good place to significantly reduce SRV.

Accordingly, the present invention provides spray apparatus comprising a pipe-work system that combines the feed and circulation lines on the spray boom to make a common feed when the machine is spraying and which converts back to recirculation when the sprayer is agitating, i.e. in a non-spraying condition. This also permits a reduction in the number of valves on the spray machine and greatly simplifies the pipe-work.

A further advantage is that the distribution of the inlets along the boom tube can be improved which means the boom tube can be smaller.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is diagrammatically illustrated, by way of example, in the accompanying drawings, in which

FIG. 1 is a flow diagram of an agricultural crop sprayer when configured for spraying, and

FIG. 2 shows the flow diagram of FIG. 1 when the spray is configured to circulate, and thus agitate the spray liquid in the spray lines.

DETAILED DESCRIPTION OF THE INVENTION

In the drawings, an agricultural crop sprayer 1, of the kind that can be vehicle mounted or towed by a tractor, comprises a source of spray liquid 2 in the form of a tank connected by pipe-work 8 to a pump 3 and thus to spray nozzles 9, so that the spray liquid can be applied to a crop.

As shown in the drawings, the pipe-work, hereafter lines, comprise a feed portion 8 a, which connects the tank 2 with the pump 3 via a suction filter 5. Downstream of the pump 3 is positioned a pressure regulator 4 which couples the feed line 8 upstream and downstream of the pump 3. Downstream of the pressure regulator, a flow meter is positioned in the feed line 8, which communicates with a feed line branch 8 b which communicates with a spray line loop 8 d having a plurality of spray nozzles 9. The loop 8 d will, in practice, be arranged to extend along the sprayer boom (not shown).

Downstream of the flow meter 5, the feed line is connected via a pressure filter 6 and a control valve 7 with a feed line branch 8 c, which is coupled to the loop 8 d at a position opposite to the junction between the feed line branch 8 b and the loop.

During spraying, the flow of spray liquid through the apparatus is as shown by arrows in FIG. 1. Thus the spray liquid flows along both feed line branches 8 c and 8 b to the spray line loop 8 d and thence to the nozzles.

When spraying ceases, the flow of spray liquid in the apparatus is shown in FIG. 2. Thus the spray nozzles are shut-off and the control valve 7 is operated to direct the spray liquid back to the tank via the feed line branch 8 c, which thus functions as a return line. It will be noted that the portion 11 of the return line downstream of the valve 7 is provided with a filling hopper by which chemical to be sprayed can be introduced into the apparatus.

The drawings thus show how the feed line enters the spray line loop at both ends. This allows pressure and flow from both ends of the spray line when spraying and a clean sweep through the lines when agitating.

The control valve 7 that permits the changeover from spray to circulation can be a conventional motorised 3 way valve assembly. As with other pressurised circulation systems the nozzles may be individually switched in banks according to the required spray boom section widths.

Thus the present invention permits:

1. The use of the return line to provide extra flow to the boom when spraying.

2. A reduction in the size of the feed lines because the return line provides extra flow when spraying.

3. The purging of the spray line under pressure when filling with chemical.

4. The use of a single control valve to control the feed and return flows.

5. The ability to clean the system by incorporating clean water into the filling point (on board tank or independent supply). 

1. Spray apparatus of the kind having a liquid feed line connecting a supply of spray liquid and at least one spray nozzle, a return line from the spray nozzle to the supply and a pump for moving spray liquid from the supply to the at least one spray nozzle and for returning spray liquid from the at least one spray nozzle to the supply when the liquid is not being sprayed, wherein the liquid return line serves as at least a portion of the feed line when spraying.
 2. Spray apparatus according to claim 1, wherein a portion of the feed line which includes the at least one spray nozzle is formed as a loop to which the return line is connected.
 3. Spray apparatus according to claim 2, wherein the return line is connected to the loop at a position opposite to the position at which the portion of the feed line from the pump is connected to the loop.
 4. Spray apparatus according to claim 1, comprising a pressure regulator and a flow meter in the feed line between the pump and the at least one spray nozzle, the pressure regulator being positioned upstream of the flow meter. 